Like it or not (I’m not sure I do!), Thai is a tonal language and you’ll need to be able to use the correct tones when speaking. Every syllable has its own tone — either mid, low, high, falling or rising.
Get it wrong, and hopefully, your listener will politely ignore your mistake. If they’re not quite so polite, they may practically fall over laughing so much. Not much fun to be on the receiving end of that again and again, so it’s well worth trying to get the tones correct.
How am I supposed to know what syllable has which tone then?
Glad you asked. When using Thai script, there’s a byzantine series of rules that govern the tone, but in transliteration we have the freedom to look for an easier way.
Our solution is to use the accent symbols as tone markers, as they look approximately reflect the sound of the tone. We’ll add one of these above the first vowel in each symbol, except for mid-tones.
Though these accent symbols weren’t at all intended for Thai, it turns out they’re accidentally perfect for showing the Thai tones.
Just like the symbols, the Thai falling tone actually rises slightly in pitch before falling, and the rising tone does the opposite. Similarly, the high and low tones actually start roughly neutral in pitch before moving up and down respectively.
The tone marker symbols mirror this in pitch, so as well as showing the tone they perform double duty by acting as a subtle reminder of how the tone should be pronounced too.